text: const CustomError = require("../extensions/custom-error");
  
  const MODERN_ACTIVITY= 15; 
  const HALF_LIFE_PERIOD= 5730;
  
  module.exports = function dateSample(sampleActivity) {
    var result = 0;
  
    if(sampleActivity == undefined || typeof sampleActivity !== "string") {
      return false;
    }
    const coff = 0.693;
    const k = coff/HALF_LIFE_PERIOD;
    var number = parseFloat(sampleActivity)
    if (isNaN(number)){
      return false
    }
    if(number < 1 || number > 15){
      return false;
    }
  
    return Math.ceil((Math.log(MODERN_ACTIVITY/number))/k);
  };
  